On Thu, May 18, 2017 at 06:08:04PM +0800, Anand Jain wrote:
> By looking at the logs we should be able to know when was the FS
> mounted and unmounted and the options used, so to help forensic
> investigations.
>
> Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
> ---
> You may want to know that, during boot and shutdown this
> adds roughly 25 lines more logs depending on the config, and it
> logs even for non block device FS, such as proc, sysfs ..etc.
> And blockdev FS only check will eliminate overlay as well, which
> is kind of defeats the purpose.
> Further, just to highlight if your test script involves mount and
> umount, which probably all of fstests does, it will add logs when
> FS is mounted and umounted.
> Still IMO, these logs are useful for the end purpose as mentioned
> above. Its for your feedback. Thanks.
XFS already logs its own unmounts. I prefer to let each filesystem log
its own unmount, because then the mount/unmount messages also have the
same prefix as all other messages coming from that filesystem driver.
> fs/namespace.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/fs/namespace.c b/fs/namespace.c
> index b3b115bd4e1e..78375b6f8330 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -1686,6 +1686,8 @@ SYSCALL_DEFINE2(umount, char __user *, name, int, flags)
> struct mount *mnt;
> int retval;
> int lookup_flags = 0;
> + struct super_block *sb;
> + char umntlog[256] = {0};
Kind of a lot of stack space...
--D
>
> if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW))
> return -EINVAL;
> @@ -1711,7 +1713,15 @@ SYSCALL_DEFINE2(umount, char __user *, name, int, flags)
> if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN))
> goto dput_and_out;
>
> + sb = mnt->mnt.mnt_sb;
> + snprintf(umntlog, sizeof(umntlog), "umount %s dev:%s flags:%d",
> + sb->s_type->name, sb->s_id, flags);
> +
> retval = do_umount(mnt, flags);
> +
> + if (!retval)
> + printk(KERN_NOTICE "%s\n", umntlog);
> +
> dput_and_out:
> /* we mustn't call path_put() as that would clear mnt_expiry_mark */
> dput(path.dentry);
> @@ -2833,6 +2843,11 @@ long do_mount(const char *dev_name, const char __user *dir_name,
> else
> retval = do_new_mount(&path, type_page, flags, mnt_flags,
> dev_name, data_page);
> +
> + if (!retval)
> + printk(KERN_NOTICE "mount %s dev:%s dir:%pd flags:0x%lX opt:%s\n",
> + type_page, dev_name, path.dentry, flags, (char *)data_page);
> +
> dput_out:
> path_put(&path);
> return retval;
> --
> 2.10.0
>
> --
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